Negative transconductance tube oscillator



Oct. 19, 1943. w. P. MASON 2,332,102

NEGATIVE TRANSCONDUCTANCE TUBE OSCILLATOR Filed NOV. 26, 1941 FIG.

FIG. 2

CRYS TAL' a up A r Tom/5v rentto the output electrode.

Patented Oct. 19, 1943 sesame a iizmsconnuo'rimcn runs a I Telephone j Laboratorieaq Incorporated; 'f

- I New York, N; Y ajcorporation of York A pliaatien steam at, 1941,: S eriaI No. 420,499

- Bell This invention relates to negative .trans'con-f; ductance tubes "and specia1- circuits combined therewith to form negative transconductance tube oscillators, amplifiersorthelike I The primary objector the present inventionl is to operate all circuit elements of suchnegative transconductance a devices I at their resistance points to insurethat the, gain through the overall circuit, isEmaXimurnand that battery, tube and other jliuctuations produce no corresponding frequency iiuctuations.

75175-1 tubeby using the .control grid and thea suppressor :screenas, the; gridand: anode re-.

SDGCt j-VQIY, and applying: prop potentials thereto, i a g The variousforinsof discharge tubes indicated 1 above have been citedas examples othe'r types Q ff-tub s ha n t ear es tivewtra sc du am characteristic;- may be used;

This object is achieved bi -team ng oi tg onant and antiresonant circuits in combination with the negative transcon d uctance discharge devices. I

A further object of my invention is to use piezoelectric crystals 1- operating at their re sis tive points in :combination with negative transconductance i discharge devices.

-' A stillfurther object of my invention is to" shown an electron discharge device I having a negative transconductance characteristic whereby an increase in-potential on the control grid electrode causes a decrease in the electroncur- The output current is therefore in phase with the applied grid potential rather than 180 degrees out of phase as in a conventional tube. Specifically, one form of discharge device which possesses these desired characteristics has been realized in a beam power pentode such as the RCA 6L6 tube, when the same is operated under the following conditions:

volts on the anode A +150 volts on the screen grid S -1.8 volts on the grid. G

The filament or cathode c, the biasing batter- Associated with the discharge tube hand co-.,

operating therewith for producing maximum eda leir u 5 91 1 a d 2.0 I

, The circuit L Ci consists of Initiation of inductance L1. and capacitance (21,

output and highf-requency stability; are two imcon-nected effectively from the anode to thecathode, which may begroundedas shown-in Figl.

71 i w sii i e ubv p m l omb ti i lumped-capacity and inherent tube capacity;

L The circuit L'cCz consists of a series combination of inductance "2L2 anglecapacitance C2 and is connected inthegpath leading from the anode to; the: gridc LzC -is resonantatthe saine irequency to WhiSZh LlQIll S antiresonant this common frequency being the frequency atwhich thecombination of tube and circuits described will 30501118176.

At the common natural response frequency,

the impedance of the series-connected circuit will be a low resistance and the impedance of {the L101 combination will also be resistivej RA denotes the inherent resistance at antiresonance v of the 'L1C1 circuit, while R13 represents the inherent resistance at series resonance of the LzCz circuit.

r The combination thus described with respect to Fig. 1 is effective in causing all the circuit elements thereof to operate at their resistance points, thereby insuring maximum gain, and since no-phase shiftsfare introduced, providing frequency stability;

inantly resistive efiect at the oscillator frequency The circuit L1C1 in Fig. Zis antiresonant at the 1 RA in Fig. 2

ies and the by-pass condensers are conventional v elements.

Similar negative transconductance character- Referring to the modification illustrated by Fig. 2, the only essential change introduced here 'is the substitution of a resonating piezoelectric crystal element P in place of the resonant combination LzC z. The crystal operates at its series resonance point with great stability and provides, as inlthe case of LzCz of Fig. 1, a predomsame frequencyas the crystal. has the same significance as in Fig. '1.

Other changes may readily suggest themselves 1 to those skilled in the art; such as the particular 1 form of negative transconductance tube or the isti 5 may obtained with aWesterri Electric a rallel ,cornparticular form of the associated resonant and antiresonant circuits.

What is claimed is:

1. An oscillation generator comprising an electron discharge device having a cathode, control electrode and anode, means associated with said three electrodes to constitute therewith. a negative transconductance translating device, a

feedback circuit betweensaid anode" and control electrode comprising an effective series resonant combination of inductive and capacitive elements tuned to a desired frequency of generat ed oscillations, and a parallel resonant circuit connected to said anode and cathode, said parallel resonant circuit being tunedtothe 'same' frequency as said series resonant circuit and comprising in part the interelectrode capacitances of said device.

2. An oscillation generator comprising an electron discharge device having a cathode, control electrode and anode, means associated with said electrodes to constitute 'a negative transconductance translating device, a feedback circuit between said anode and control electrode comprising an efiective series resonant combination of inductive and capacitive elements tuned to a desired frequency of generated oscillations, anda parallelresonant circuit connected to said anode and cathode, saidparallelresonant circuit being tuned to the same frequen 7 resistive at the characteristic piezoelectric crystal frequency.

5. An oscillation generator comprising an electron discharge device provided with cath- 'ode, anode, screen grid and control grid electrodes, means associated with said electrodes to constitute therewith a negative transconductance translating device, an antiresonant circuit connected between said anode, screen grid and cathode and comprising in part the interelectrode capacitances of said discharge device,

a feedback path connected from the anode to the control grid and containing therein a series resonant circuit, both resonant and antiresonant circuits being resistive at 'the same predetermined frequency to provide maximum output'and greatest frequency stability. 6. An oscillation generator comprising an electron discharge device provided with cathode, anode, screen grid and control grid electrodes, means associated with said electrodes to constitute therewith a negative transconductance translating device, an antiresonant circuit connected between said anode, screen grid and cathode and comprising in part the intere1ectrode capacitances of said discharge device, a feed back path connected from the anode to the control grid and containing therein a piezoelectric crystal impedance element, said antiresonant circuit being predominantly resistive at the characteristic piezoelectric crystal frequency.

i j WARREN P. MASON. 

